Using data from the OPEN study, LERs and non-LERs keep identified with DLW, were compared with respect to three aspects of food group reporting (reported consumption, frequency of consumption, and portion size) on an FFQ in 440 women and men. In the last decade, previous studies have analyzed differential reporting of foods/food groups by LER status utilizing a number of different dietary assessment tools: 24-HRs (12
), dietary records (9
), and FFQs (10
). Only one other previous study (26
) also identified LERs using DLW, but this study was small (n=50) and did not evaluate multiple aspects of food group reporting. No previous study has investigated simultaneously all three aspects of food group reporting with respect to LER status on an FFQ.
This study identified 50% of women and men as LERs, a greater percentage than identified in other non-DLW studies analyzing differential reporting of foods by LER status. These studies identified, when a dichotomized EI:BMI ratio was used, anywhere from 14 % (26
) to 40% (16
) of persons as LERs. In the study by Svendsen and Tonstad (26
), which used DLW, 52% of men and 59% of women were identified as LERs, a slightly greater percentage than observed in OPEN.
Not many differences were observed between LERs and non-LERs with respect to whether they reported certain food groups. Only women (not men) LERs differed from non-LERs in whether they reported consumption of food groups, but only for two food groups (soft drinks/regular and soft drinks/diet). Perhaps this is because, on the FFQ, participants were asked to estimate how often, over the course of an entire year, they ate a certain food group. This resulted in estimates for many food groups that were over 90%, making it difficult to distinguish differences in food group reports between LERs and non-LERs. The majority of food groups, 37 of 43 (86%), were reported as being consumed over the past year by 50% or more participants in any subgroup.
However, differential reporting by LER status with respect to daily frequency of consumption of food groups was consistent with similar findings in the literature (12
). This differential reporting may relate to social desirability bias, such as the tendency for LERs versus non-LERs to report sweets and desserts less frequently, whereas other differences may relate to cognitive difficulties. An example of the latter would be LERs reporting snack foods, nuts/seed, fruit and crackers less frequently than non-LERs. Perhaps LERs have more difficulty estimating frequency of snack food intake because consumption may occur over the course of a day or week in a grazing-type manner. At the same time, most food groups, with the exception of cooked cereal, ready-to-eat cereal, pizza, green salad, milk (on cereal, in coffee or tea, and as a beverage), yogurt, wine, liquor, coffee/tea, cream/creamer/liquid, cream/creamer/not whipped, and dressing/not may-type were differentially reported between LERs and non-LERs with respect to frequency of consumption. This suggests that LERs' tendency to underreport frequency of consumption may not be specific to any one food group but more general across all food groups.
In this FFQ study, participants were asked to recall intake over the last year. It is possible that a shorter recall period (i.e., 3 months) would have resulted in less food groups that were reported differentially between LERs and non-LERs with respect to frequency of consumption. Only one other study has analyzed differential reporting of food frequency consumption by LER status (15
) with an FFQ. However, this study did not mention the time frame that their FFQ captured.
In addition to frequency of consumption, some food groups were more likely to be reported as consumed in smaller portion sizes by LERs as compared to non-LERs. The number of food groups (<10) for which portion sizes were likely to be reported as smaller among LERs as compared to non-LERs was less than the number of food groups (>20) for which LERs compared to non-LERS reported with less daily frequency of consumption. Food groups that are served as mixed dishes, such as pasta/pasta mixture and meat/fish/poultry/egg sandwich mixtures, were reported with smaller portion sizes among LERs compared to non-LERs in both men and women. These were the only food groups for which both men and women LERs as compared to non-LERs also reported with a lower daily frequency of consumption. Mixed dishes may be one food group for which people have more cognitive difficulties estimating portion size than other food groups, and this challenge may be greater for LERs than non-LERs. For example, on the DHQ, portion size of a pear is defined as small (< 1 pear), medium (1 pear), or large (> 1 pear). Differently, portion size for lasagna/stuffed shells/stuffed manicotti/ravioli/tortellini is defined as small (< 1 cup), medium (1-2 cups), and large (> 2 cups).
Differences between how LERs and non-LERs reported food group intake did not vary greatly by sex. Men and women had a similar number of food groups, as well as similar types of food groups, reported as consumed less frequently and with smaller portion sizes in LERs as compared to non-LERs. Additionally, effect modification of the relationship between food reporting and LER status by BMI was investigated as previous results in OPEN showed that men LERs were more likely to have larger BMIs (8
). However, differences in food reporting between LERs and non-LERs only varied statistically significantly by BMI status for a few foods and only with respect to frequency of consumption.
It is unclear whether all differences in frequency of consumption or portion size estimates between LERs and non-LERS represent true underreporting by LERs. It is possible that LERs and non-LERs simply have different dietary patterns of intake. Although participants were told not to diet during OPEN, and the participant weight loss patterns do not suggest dieting, it is possible that LERs have adopted food habits of “dieters” (such as drinking diet soda), even if they were not currently dieting. In OPEN, a greater percentage of LERs than non-LERs have reported dieting in the past (8
), and may have adopted some of the dieting behaviors from their past, such as women LERs drinking regular soda less frequently. However, the present study cannot determine why
LERs and non-LERs are more or less likely to differentially report frequency of consumption and portion size estimates